As a wire harness for automobile and motorcycle use, an electrical wire bundle formed by binding together a plurality of insulated electrical wires with a cable tie, adhesive tape, or the like is used. Each of the insulated electrical wires is typically formed by covering, with an insulating material, a bundle of one or a plurality of strands made of a conductor such as a copper alloy. The strands are exposed at a connecting portion (joint) located at the end or middle of such an electrical wire bundle, and thus it is necessary to make such a portion waterproof. In order to achieve this waterproofing, a heat-recoverable component such as a heat-shrinkable tube or a heat-shrinkable cap is used. This heat-recoverable component includes, for example, a cylindrical base material layer and an adhesive portion disposed on the inner circumferential surface of the base material layer. When the connecting portion is covered with such a heat-recoverable component and heating is performed, the heat-recoverable component shrinks so as to conform to the shape of the connecting portion and comes into close contact with the connecting portion, thus achieving waterproofing of the connecting portion.
In waterproofing a wire harness, it is required to prevent entry of water from the outside into a connecting portion, and it is also required to block entry of water into gaps between strands disposed inside an insulated electrical wire. This water blocking between strands can prevent water from entering a connected device through insulated electrical wires disposed inside the device. However, since the adhesive used in the existing heat-recoverable component has a high viscosity, a process of simply thermally shrinking the heat-recoverable component does not cause the adhesive to sufficiently penetrate between strands, and it is not possible to sufficiently block entry of water into gaps between the strands.
In view of this, methods for blocking water between strands have been proposed in which an adhesive or a water-blocking agent having a low viscosity is injected from a connecting portion to block entry of water into gaps between strands, and a heat-recoverable component is then placed over the connecting portion and is thermally shrunk (refer to Japanese Unexamined Patent Application Publication Nos. 11-233175 and 2009-99385).